Power-law response of metal oxide semiconductor gas sensors to oxygen in presence of reducing gases

This study presents a theoretical and experimental investigation on the power-law response to oxygen in the presence of reducing gases for metal oxide semiconductor gas sensors. In the presence of reducing gases, the exponents of power-law response to oxygen are derived, which allow us an effective probe to reveal the basic sensing mechanism. In order to obtain the power-law exponent, the transducer and receptor functions have been calculated in the presence of reducing gases. The transducer functions is built on two different conduction mechanisms, namely, Schottky barrier model and grain model. The receptor functions have been calculated by using the law of mass action for oxygen with different concentrations of reducing gases. The power response of SnO2 to oxygen has been characterized in the presence of CO and found to be well consistent with theoretical expectation.